The project is designed to study the effects of chronic heroin or methadone use during pregnancy upon the developing fetus. The role of nutrition, infection, and other complications during pregnancy will be evaluated. Infants born to heroin addicts, methadone-maintained mothers and matched controls will be evaluated in the newborn period and at selected intervals through two years (to be extended through school age). Data to be analyzed includes birth measurements, maturity at birth, neurologic status, major and minor anomalies, and degree of abstinence syndrome. Screening studies for intrauterine infection will be done. Routine assessment of growth, development, and behavior will ensue.